JP2022520087A - Integrated transformer with low AC loss and impedance balancing interface - Google Patents

Abstract

The integrated transformer device has both an inductive element and a transformer element. Inductive and transformer elements are combined within the same device and share at least part of the same magnetic and electrical path. The integrated transformer device includes an upper core, a lower core, and a shunt core. A high voltage winding is wound around the lower core. Low voltage windings are wound around the lower core and shunt core. Power semiconductor devices connected in parallel form part of a low voltage winding and are placed in close proximity to the high voltage winding.

Description

The present disclosure relates broadly to transformers, and more specifically to integrated transformers with low alternating current (AC) power loss.

A converter is a device that converts electrical energy from one form to another and is typically used to convert one voltage to another.

Resonant converters and resonant transition converters rely on either series induction components or transformer integrated inductors to provide inductance, which together with the added capacitance form a resonant tank. These resonant converters and resonant transition converters utilize resonant tanks and soft switching technology to achieve low loss and high efficiency conversion.

For isolated converter topologies, transformers are often required to provide insulation, as well as to increase or voltage the voltage using the turns ratio. Since such converters require both inductive and transformer elements, it would be desirable to combine both functions into the same component.

Earlier transformer systems, such as those described in Patent Document 1, entitled "High-Frequency Power Transformers" by Alexander Isurin et al., Disclose transformers with low AC conduction loss. There is. The low loss is due to the close proximity of the primary and secondary windings. However, this system is a parallel connected power semiconductor such as a field effect transistor (FET), diode, or insulated gate bipolar transistor (IGBT) in a large current path with balanced impedance interconnection to a large current winding. Does not provide even distribution of current between devices. To reduce power consumption and stress on components and increase the overall reliability of the power converter, it is desirable to distribute the current evenly. Moreover, configurations of these power semiconductor devices, such as metal oxide semiconductor field effect transistors (MOSFETs), diodes, or IGBTs, as disclosed, cannot complete one winding of the winding and thus increase loss. Brings. In addition, the additional drawback of such transformers is the high leakage inductance suitable for the resonant converter to operate over a wide input voltage range without inserting a large gap between the primary and secondary windings. It cannot be achieved high enough. However, a large gap between the primary and secondary windings is not desirable as it will significantly increase the AC loss of the windings.

Patent Document 2 entitled "Transformer with Integrated Inductor" by Bernd Ackermann discusses the integration of inductive elements into a transformer. However, since the primary winding and the secondary winding do not overlap, this results in a very high AC conduction loss. An additional example of higher loss is a "planar transformer with a single planar winding board and two magnetic cores" by Jin He et al., Which integrates the inductor and the transformer but maintains a separate core. And an output inductor structure (Planner Transformer and Output Inductor Structure with Single Planar Winding Board and Two Magnetic Cores) can be found in Patent Document 3. Separation of the core does not share the magnetic flux or conduction path, contributing to greater loss.

Guisong Huang et al., "Combined Transformer-inductor Device for Application to DC-to-DC Converter with Silicon" patent with Synchron, "Combined Transformer-inductor for DC-DC converters with synchronous rectifiers" Even when the inductive element and the transformer are integrated into the same core, as shown in Ref. 4, the electrical separation of the inductive element and the transformer still cannot produce a useful resonant converter. .. In fact, even if the same core is used for the inductive element and the transformer, separating the primary and secondary windings will result in "Methods and means of combining transformers and inductors in a single core structure" by Carl Keuneke. And Mens for Combining a Transformer and Inductor on a Single Core Structure) ”, as shown in Patent Document 5, the AC conduction loss becomes high. Patent Document 6 entitled "Integrated Transformer and Inductor" by Victor Roberts results in the separation of the primary and secondary windings even for a portion of the core within the same core. It shows the problem of increasing AC loss. Moreover, the separation in this case prevents providing a balanced impedance interconnection between the high current winding and the power semiconductor device connected in parallel.

U.S. Pat. No. 7,123,123 U.S. Patent Application Publication No. 2002/01673885 U.S. Pat. No. 6,927,661 U.S. Pat. No. 6,714,428 U.S. Pat. No. 5,783,984 U.S. Pat. No. 4,613,841

Therefore, it would be desirable to provide a transformer that integrates the inductive and transformer elements into a single device. It would be even more desirable to provide a transformer with low AC conduction loss. In order to further reduce conduction losses, it would be even more desirable to provide transformers with balanced impedance interconnections between high current windings and power semiconductor devices.

This provides a system that includes a device with both inductive and transformer elements. The system can further provide the device with inductive and transformer elements that share at least a portion of both the magnetic and electrical paths.

This system can further reduce space and weight, and can reduce conduction loss and core loss. According to one embodiment, the system can minimize or eliminate significant AC conduction losses and provide a balanced impedance connection with power semiconductor devices.

According to one embodiment, an apparatus comprising both an inductive element and a transformer element is disclosed. Inductive and transformer elements are combined within the same device and share at least part of the same magnetic and electrical path. According to one embodiment, conduction loss and core loss are reduced to provide a well defined path for leakage flux in an integrated transformer.

As disclosed herein, the apparatus, according to one embodiment, utilizes a large current and is balanced with a power semiconductor device such as a FET, diode, or IGBT connected in parallel. Provides an impedance connection. In a further embodiment, the power semiconductor device can complete one or more turns of the transformer winding. Such a low impedance interconnect further reduces the conduction loss of the transformer by reducing the AC loss. This further provides the advantage of preventing current concentration at the terminals. Therefore, an integrated transformer / inductor device with balanced impedance connections to parallel connected power semiconductor devices in high current windings is provided for use in high frequency resonant mode switching power converters.

The aforementioned embodiments of embodiments and circuit configurations disclosed herein, as well as other advantages and benefits, are apparent from the more detailed description below, which can be understood with reference to the accompanying drawings. , Similar names refer to similar elements.

An integrated transformer according to an embodiment is shown. FIG. 1A is a bottom perspective view of the integrated transformer. An integrated transformer according to an embodiment is shown. FIG. 1B is a top perspective view. An exemplary embodiment of an integrated transformer with a transformer holder is shown. An exemplary embodiment of a transformer device comprising a power semiconductor device is shown. An exemplary embodiment of the electrical and magnetic interconnection of a transformer is shown. A cross section of a transformer according to an embodiment is shown. Another embodiment of a transformer with alternative positions for FETs or diodes is shown. The figure of the prior art of the parallel rectifier which is poorly arranged is shown. An embodiment of the present invention comprising a power semiconductor device connected in parallel and a balanced interconnection impedance is shown. The figure of the prior art of the proximity effect is shown. The relationship of the flow of AC current which concerns on one Embodiment is shown. The current density of the FETs connected in parallel according to one embodiment is shown. Another embodiment of a transformer with a removable electrical connection is shown.

An exemplary embodiment is described herein with reference to the systems shown in FIGS. 1A and 1B. The transformer 101 includes a core formed from three sections: an upper core 105, a lower core 107, and a shunt core 109, the shunt core 109 including an array of distributed gaps 125.

In one embodiment, the transformer 101 can be a transformer with a rating of 7 kW. However, it should be noted that the transformer 101 can be rated for other suitable high current or high power transformers. For example, the high current can be tens to thousands of amps, or any other suitable amount. In a further example, high power can range from hundreds of watts to hundreds of thousands of watts.

According to one embodiment, the shunt core 109 can be made of a low magnetic permeability magnetic material such as powder metal. However, the shunt core 109 can also be formed as a segmented core of a higher magnetic permeability material such as ferrite. The choice of shunt core material will depend on a variety of factors, including switching frequency, maximum flux density, and core size. The shunt core 109 can be formed of any suitable material, such as an additional type of low magnetic permeability magnetic material, or an additional form of high magnetic permeability material. For example, in certain embodiments, the shunt core 109 can be made of sendust or powdered iron.

In the embodiments of FIGS. 1A and 1B, the upper core 105 is located above the lower core 107. The upper 105 core can be physically engaged or fitted with the lower core 107 in order to maintain the relative positioning of both cores. The shunt core 109 is located adjacent to the lower core 107 and can be physically engaged or fitted to the lower core 107 in order to maintain the relative positioning of both cores. In an embodiment, a holder (shown as holder 215 in FIG. 2) and an adhesive (not shown) are used to maintain the relative positioning of the cores 105, 107, and 109.

The integrated transformer 101 further includes a high voltage winding 111. The high voltage winding 111 can be formed by a plurality of windings such as 9 windings. Of course, the optimum number of turns will depend on the design goals for the particular intended use. The wire gauge used for winding 111 depends on the power level of the transformer and can consist of, for example, a single 16 gauge wire or a plurality of parallel thicker gauge wires. That is, the high voltage winding 111 conducts a lower current, but can be configured as a plurality of windings with a higher applied voltage. For example, the high voltage winding 111 can be connected to a power semiconductor device, but the current in that winding can be lower, so AC loss is not important and thus equilibration to those multiple power semiconductor devices. May not require a good impedance connection. The voltage level of the high voltage winding 111 is not constrained to a particular value and can be, for example, in the range of about 50-100,000 volts. However, in some embodiments, suitable high voltage levels can range from about 200 to 800 volts.

The integrated transformer 101 further includes a low voltage winding 113. The low voltage winding 113 is a single winding and conducts a high current, but can be due to a lower applied voltage. In the embodiments shown in FIGS. 1A and 1B, the low voltage winding 113 is made of flat metal parts preformed into the required shape. Due to the high current conducted through it, the low voltage winding 113 is balanced for connecting to the configuration of multiple power semiconductor devices connected in parallel as described below with reference to FIG. Includes a good impedance interconnect.

In this embodiment, the high voltage winding 111 inserted between the upper core 105 and the lower core 107 and between the lower core 107 and the shunt core 109 is wound around the lower core 107. The constant voltage winding 113 inserted between the upper core 105 and the lower core 107 is wound around the lower core 107, the high voltage winding 111, and the shunt core 109.

As shown, windings 111 and 113 are arranged in close proximity to each other over most of the length of the winding. For example, the high voltage winding 111 and the low voltage winding 113 can be separated by a distance of 0 to 0.25 times the width of the high voltage winding 111. In this embodiment, the width of the high voltage winding 111 is about 2.5 inches (63.5 mm). The windings 111 and 113 can be insulated so that they are electrically isolated from each other even when they come into contact with each other. Due to the proximity effect, the windings 111 and 113 should be placed as close to each other as possible within the mechanical tolerance to provide a more uniform distribution of current densities over the surface of the windings 111 and 113. Is preferable. In contrast, if the windings 111 and 113 are not in close proximity to each other, in other words, if the windings 111 and 113 are separated by more than about 0.25 times the width of the high voltage winding 111, then the current Most are concentrated at the edges of the low voltage windings, which significantly increases AC loss. However, here, due to the proximity effect, the current is not concentrated on the edge of the low voltage winding, so the AC loss is minimized.

FIG. 2 shows a holding device of the transformer 101. As shown, the holder 215 maintains the arrangement of windings 111 and 113, as well as the upper core 105, lower core 107, and shunt core 109. Therefore, the holder 215 keeps all the parts in place and positions them correctly. The holder can be formed from a non-magnetic, non-conductive material such as injection molded plastic.

In this embodiment, the shunt core 109 is formed from several segments 217 that are properly spaced from each other and from the lower core 107 by the transformer holder 215. The gap 225 between the individual shunt segments is controlled by the transformer holder 215 to be between 0% and 25% of the length of the shunt segment 217. The desired gap distance depends on the design goals and can be calculated directly based on various parameters such as required power capacity, allowable loss, core flux density, and amount of leakage inductance required for the transformer. An array of small gaps 225 (also known as dispersion gaps 225) provides a large total gap distance, but contains magnetic flux. Therefore, compared to a single large gap, the distributed gaps in the shunt core do not significantly form fringes in the transformer windings where the magnetic flux from the distributed gaps increases the conduction loss of those windings. Therefore, it provides more efficient performance. The number of shunt segments 217 varies depending on the desired gap distance and can range from 1 to 7 segments 217 in some embodiments.

Note that in some embodiments of the invention, the shunt core 109 can be configured as a solid self-supporting core instead of a plurality of shunt core segments 217, such as those shown in FIG. Should be.

Here, with reference to FIG. 3, a transformer 101 integrated with a power semiconductor device 310 connected in parallel is shown. In FIG. 3, the power semiconductor device 310 is attached to a printed wiring board or direct bonding copper (BDC) substrate 315 on the substrate side facing the transformer cores 105, 107, and 109. FIG. 3 shows the close interconnection between the low voltage winding 113 and the power semiconductor device 310. The power semiconductor device 301 at the position shown completes one winding of the winding, thereby significantly minimizing the distance required for the large current of the winding 113 to travel. Therefore, since the power semiconductor device itself is physically part of the winding length, the distance that the current would otherwise have to pass through the conductor is significantly reduced. In high current converters, the distance that a high AC current must travel in a conductor is directly related to the loss, so reducing the distance that a current must travel will significantly reduce the loss.

Further, in this embodiment, the high voltage winding 111 is arranged sufficiently close to the power semiconductor device 301 connected in parallel, and due to the proximity effect from the high voltage winding 111, one of the physical transformer windings 113. The current is evenly distributed among the parallelized power semiconductor devices 301 which are the units. Even distribution of current improves reliability and reduces overall power loss.

Moreover, the larger physical size of the power device, i.e., the power semiconductor device 301, significantly reduces the electrical length of the low voltage transformer winding 113 when inserted as part of the winding. Therefore, utilizing the larger power semiconductor device 301 will be more helpful in reducing the conduction loss of the transformer.

Here, with reference to FIG. 4, a diagram of the electrical and magnetic interconnections of the transformer 101 and the rectifier (power semiconductor device) 301 is shown, showing the AC and DC electrical paths.

FIG. 5 shows the physical interconnection between the rectifier 310 and the transformer winding 113, and the printed wiring circuit board 315. According to various embodiments, either FETs, diodes, or IGBTs 301, collectively referred to as power semiconductor devices, are used to rectify AC current to DC current or to convert AC current from DC current. can do. This allows the low voltage winding 113 to be either a power input or a power output. Although not shown in FIG. 5, the power semiconductor can also be connected to the high voltage winding 111 and the transformer 101 can be used for either one-way or two-way power conversion.

FIG. 6 shows, in contrast to FIG. 3, another embodiment with an alternative position for the power semiconductor device 301 connected to the transformer 101. In this embodiment, the power semiconductor device 310 is mounted on the opposite side of the circuit board or board 315 with respect to the transformer cores 105, 107, and 109. This embodiment is a power that forms part of a low voltage winding and provides a balanced impedance connection to a transformer while facilitating direct contact of a power semiconductor device with a heat sink (not shown). It retains the advantages of semiconductor devices. Therefore, when the power semiconductor device comes into direct contact with the heat sink, the circuit board is no longer part of the thermal path and thermal performance is improved. In this embodiment, the power semiconductor device can also be removed without the need to remove the transformer, facilitating ease of rework.

Therefore, the transformer 101 provides the integration of the inductor and the transformer in the same component. As shown, both parts of the magnetic flux path and the electrical conduction path are shared between the inductor element and the transformer element, thereby providing reduction of conduction loss and core loss. In addition, the use of a single integrated component is smaller in size and lighter in weight than when using separate transformers and inductors.

Placing the high voltage winding 111 proximal to the low voltage winding 113 reduces AC loss. The electrical paths of these two windings diverge only in a small portion of their total path length, i.e. between 5% and 30% of the winding length, which does not significantly increase the loss.

The shunt core 190 provides a well-defined leakage flux path that does not significantly increase AC loss, and the leakage inductance can be adjusted accurately and widely by changing the dispersion gap of the shunt core. Therefore, reducing the dispersion gap distance of the shunt core increases the leakage inductance, and increasing the dispersion gap distance of the shunt core decreases the leakage inductance. The leakage inductance generated by the shunt core 109 can be used to create a resonant tank, along with the addition of capacitance, such a resonant tank can be utilized in a resonant DC / DC converter.

The parallel power semiconductor device 301 is connected to the low voltage winding 113 and is connected to the transformer with a balanced impedance connection. The connection impedance is determined by the length of the electrical path connecting the power semiconductor device 301 to the low voltage winding 113. In this balanced impedance connection, the power semiconductor device 301 is arranged such that each device 301 has the same electrical path length to the low voltage winding 113, thus balancing the impedance connection. Here, the low voltage winding 113 is connected to the circuit board 315 by an elongated terminal 823, and the power semiconductor device 301 is connected to the terminal 823 (shown in FIG. 8). The terminal 823 has a length dimension that is at least 10: 1 longer than the width dimension. Terminals 823 can be formed in an array of pins that facilitate soldering to a printed wiring board. In one embodiment, the power semiconductor devices 301 are arranged in two rows between the transformer terminals 823, separated in each row at approximately equal intervals, and can be connected in parallel to the terminals 823. Equidistant spacing of the power semiconductor device 301 is important for achieving optimal current balance. The length of the power semiconductor device row is between 75% and 125% of the width of the low voltage winding 113. This physical arrangement of the parallel power semiconductor device 301 and their connection to the low voltage winding 113 via the transformer terminal 823 form a balanced impedance connection between the power semiconductor device and the low voltage. .. As a result of this physical placement of the component, the electrical path length of the high current conducted in the low voltage winding is minimized, thereby minimizing the conduction loss. In addition, the power semiconductor device 301 forms part of the low voltage winding itself, thereby further minimizing conduction loss. Also, due to the proximity effect from the current in the high voltage winding 111, the current is evenly distributed among the parallelized power semiconductor devices 301, thereby minimizing the conduction loss in the power semiconductor device 301. ..

As disclosed, the interconnection impedance between the transformer connection and the power semiconductor device 301 connected in parallel is balanced. In other words, the impedance between the transformer and each power semiconductor device is equal. This equal interconnect impedance provides a balanced current flow between power semiconductor devices when connected in parallel with winding 113. Therefore, the transformer specifically comprises a plurality of power semiconductor devices connected in parallel in order to realize the current transmission capacity required for the transformer. If the AC impedance between multiple parallel interconnect devices is not balanced, a balanced connection in parallel is important because the current will not be evenly distributed among those devices. The imbalanced interconnection impedance between multiple power semiconductor devices 301 in parallel results in non-uniform current, which in turn leads to increased power loss and associated increased levels of component stress. , Leads to a decrease in the reliability of the power converter.

Here, with reference to FIG. 7, an example of a poorly arranged rectifier connected in parallel in a full bridge configuration is shown. With this configuration currently known in the art, AC current flows primarily to the power device closest to the transformer terminal 723. Therefore, as shown in FIG. 7, the existing system transforms the AC current as shown by the arrow line because the power semiconductor device located closest to the transformer terminal 723 has the lowest interconnection impedance. Flow toward the device terminal 723. As a result, other power semiconductor devices further away from the transformer terminal 723 carry almost no current.

As shown in FIG. 8, one embodiment of the invention addresses the problem of FIG. 7 by providing a balanced impedance interconnect for a power semiconductor device. Transformer terminals 823 are shown in a parallel layout closer to each pair of power semiconductor devices. This layout provides approximately equal current distribution between devices connected in parallel. As a result, the interconnection impedance between the devices connected in parallel is balanced, and as a result, the current is evenly distributed to each device.

As mentioned above, the proximity effect of the high voltage winding current minimizes the conduction loss of the power semiconductor device. This proximity effect evenly distributes the current between the parallelized power semiconductor devices, thereby minimizing conduction loss.

However, in some scenarios, uneven sharing of current due to slight differences in voltage drops between devices connected in parallel or high frequency AC effects that can push current to power devices on the outer edge. May occur.

FIG. 9 illustrates this problem and shows the proximity effect caused by the AC currents flowing in adjacent conductors, where the AC currents in each conductor flow in opposite directions. As the currents flow in opposite directions, the currents tend to concentrate along the edges of the conductors closest to each other.

According to one embodiment of the invention, this problem is solved by using proximity effects to generate uniform currents between power devices interconnected in parallel. Due to the proximity effect, the AC current is evenly distributed over the surface of the conductor closest to the high voltage winding, regardless of whether the conductor is the high voltage winding 113 or the power semiconductor device 301. The width of the voltage winding 111 can be between 75% and 125% of the width of the low voltage winding 113. Approximately equal widths between high and low voltage windings result in an even distribution of current across the surface of the low voltage windings and a reduction in conduction loss.

Referring to FIG. 10, the relationship of AC current flow between the high voltage winding 111 and the power semiconductor device 310 connected to the low voltage winding 113 is shown. Since the winding currents flow in opposite directions, the current flow is evenly distributed across the power semiconductor devices connected in parallel. That is, the present embodiment provides parallel connected power semiconductor devices 301 that function as a single conductor. Be distributed.

The result of the evenly diffused current is shown in FIG. 11, which shows the current density of the FET 301s connected in parallel. This figure shows only the FETs and interconnects in the printed wiring board 315. As shown, the current densities in the interconnection between power devices connected in parallel are approximately equal. This is due to impedance balancing and the proximity effect of the high voltage windings located just above the FET.

By using the above advantages, the current capacity of the power converter can be scaled to higher current levels by increasing the length of the transformer and increasing the number of FETs connected in parallel. Therefore, even at very high switching frequencies, the current can be evenly distributed among a large number of power semiconductor devices connected in parallel.

In further embodiments, such as when the transformer 101 is used in a lower power converter, the power semiconductor devices do not need to be arranged in a parallel configuration. However, such embodiments reduce the AC loss on the printed wiring board or board 315, reduce the AC loss on the low voltage winding 113, and leak large enough to be used in a resonant DC / DC power converter. The same basic mechanical configuration as disclosed herein is still utilized because it is advantageous for generating inductance.

FIG. 12 shows an additional embodiment in which the transformer is removable from a printed wiring board or direct bonding copper substrate (DBC) 315 without the need to remove solder connections. As shown, the transformer can be electrically connected to a power semiconductor device by using bolts or other types of fasteners 335 and multi-component low voltage windings 113A.

A further advantage of the embodiments disclosed herein is that the power output capacity of the transformer device 101 can be expanded to about 10,000 watts, whereas conventional transformers with the same footprint are about 1, It can only output 000 watts. This approximately 10x increase in output power capacity uses a balanced impedance output that produces an even distribution of current to all power semiconductor devices 301, and lengthens the transformer as needed. Due to the design that allows additional semiconductor devices to be added to increase the current output capacity.

The disclosed content has been described and illustrated with respect to the exemplary embodiments provided herein, but those skilled in the art will be disclosed herein as described in the claims below. It will be appreciated that various additions and modifications can be made to these disclosed embodiments without departing from the spirit and scope of the innovation.

Claims (18)

A core having an upper core, a lower core, and a shunt core, wherein the upper core is arranged upward and fitted to the lower core, and the lower core is fitted to the shunt core.
A high voltage winding that is inserted between the upper core and the lower core and between the lower core and the shunt core and wraps around the lower core.
A low voltage winding that is inserted between the upper core and the lower core and surrounds the lower core, the high voltage winding, and the shunt core.
The first low voltage winding terminal and the second low voltage winding terminal,
A circuit board provided with the first and second low voltage winding terminals, wherein the first and second low voltage winding terminals are connected to the low voltage winding and surround the low voltage winding. With the circuit board, which completes one winding of the wire, the circuit board is located below the lower core and in close proximity to the high voltage winding.
A transformer device comprising a plurality of power semiconductor devices mounted on the circuit board and connected to the first and second low voltage winding terminals. The transformer device of claim 1, wherein the first and second low voltage winding terminals have a length and a width, each of which is significantly longer than the associated width. The power semiconductor device is arranged in two rows at approximately equal distances within each row between the first low voltage winding terminal and the second low voltage winding terminal on the circuit board. The transformer device according to claim 2, which is arranged. The transformer device according to claim 3, wherein each power semiconductor device row extends to a length of 75% to 125% of the width of the low voltage winding. The transformer device according to claim 4, wherein the power semiconductor device mounted on the circuit board is arranged in the vicinity of the high voltage winding. The transformer device according to claim 5, wherein the power semiconductor device is arranged close to the high voltage winding at a distance of 0 to 0.25 times the width of the high voltage winding. The transformer device according to claim 6, wherein the power semiconductor device is connected to the first and second low voltage winding terminals in a parallel configuration. The transformer device according to claim 1, wherein the circuit board is a printed wiring board or a direct bonding copper board. The transformer device according to claim 3, wherein the power semiconductor device is arranged on the upper surface of the circuit board so as to face the transformer core. The transformer device according to claim 3, wherein the power semiconductor device is arranged under the circuit board so as to face the side opposite to the transformer core. The transformer device according to claim 7, wherein the connected power semiconductor device is configured to form a rectifier circuit. The transformer device according to claim 7, wherein the connected power semiconductor device is configured to form a drive circuit. The transformer device according to claim 1, further comprising a transformer holder that maintains the relative positions of the windings and the core. The transformer device according to claim 1, wherein the shunt core includes a plurality of core segments separated from each other by at least one gap. The transformer device according to claim 1, wherein the shunt core includes a single core segment composed of a low magnetic permeability magnetic material such as a powder metal material. The transformer device according to claim 1, wherein the low voltage winding has a multi-component structure for detachably connecting the transformer device to the circuit board or the board. A method of distributing current among multiple power semiconductor devices connected to the low voltage windings of a transformer.
With steps to provide a transformer device with a magnetic core, low voltage windings, and high voltage windings,
A step of mounting a power semiconductor device on a circuit board with a pair of opposed elongated terminals, wherein the power semiconductor device is located between the elongated terminals in two rows at approximately equal distances within each row. And the steps placed in
The step of connecting the power semiconductor to the elongated terminal,
A step of connecting the elongated terminal to the low voltage winding so that the power semiconductor completes one winding of the low voltage winding.
A method comprising placing a semiconductor device near the high voltage winding. 17. The method of claim 17, further comprising winding the high voltage winding to a width between 75% and 125% of the width of the low voltage winding.

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